Correction of off resonance-related distortion in echo-planar imaging using EPI-based field maps.
We present, here, a simple method for measurement and correction of off-resonance related geometric distortion in echo-planar imaging (EPI). This method uses high signal-to-noise ratio (SNR) EPI-based field maps, rapidly acquired using a series of gradient recalled images collected across a range of TE values. This field map is distorted in the same manner as the EPI images to be unwarped, providing a direct look-up table for the correct location of each pixel of data. This method adds very little scan time and is robust and easy to implement.
Reber
P J
PJ
Department of Psychiatry, University of California, San Diego 92103, USA.
Wong
E C
EC
Buxton
R B
RB
Frank
L R
LR
D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods